Developmental apraxia of speech (DAS) has been described as a disorder of praxis which results in significantly impaired communication skills. Many children with DAS produce unintelligible speech, making verbal communication extremely challenging. It has been hypothesized that impaired speech motor control may underlie speech difficulties in this population. There is currently little known, however, about the motor speech skills of children with DAS, particularly with regard to articulator movement. To address this gap in knowledge, we will compare how children with DAS and their age-matched, typically developing, peers alter their articulatory movements during speech tasks with varying linguistic demands. Twenty children with developmental apraxia of speech and twenty age-matched children with typically developing speech and language skills will be included in the study. Lip and jaw kinematics will be examined using an optical motion capture system as participants produce one, two and three syllable words. The specific aims are (1) To determine whether the duration, displacement and velocity of articulator movements differ between children with developmental apraxia of speech (DAS) and those with typically developing speech and language skills;(2) To determine whether articulator movement variability differs between children with developmental apraxia of speech (DAS) and those with typically developing speech and language skills (TD);and (3) To determine whether articulator movement variability changes as children with developmental apraxia of speech (DAS) produce speech that increases in linguistic complexity. The broad, long-term objective of this research is to identify components of the speech motor system that break down during development in children with impaired speech. Understanding the relationship between speech motor control and sound production in children with DAS will shed light on the etiology of the disorder, as well as the speech characteristics associated with it. This will have an important impact on the differential diagnosis of DAS, as well as therapeutic intervention. Relevance: Developmental apraxia of speech will impede a child's ability to communicate, which can also extend to social, academic and emotional aspects of development. This work will examine oral articulator movement in children with DAS in order to understand the relationship between speech motor control and sound production in this population. The health relatedness of this project lies in the important impact it can have on the differential diagnosis of DAS and on therapeutic intervention, both of which will lead to improved communicative skills in children.